Exterior shell of a truck cab steps unit



FIG 1 is a top, side perspective view of an exterior shell of a truck cab step unit showing our new design;

FIG. 2 s a side elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a top, side perspective view of an exterior shell of a truck cab step unit showing a second embodiment of our new design;

FIG. 5 is a side elevation view of FIG. 4;

FIG. 6 is a top plan view of FIG. 4;

FIG. 7 is a top, side perspective view of an exterior shell of a truck step unit showing a third embodiment of our new design;

FIG. 8 is a side elevation view of FIG. 7; and

FIG. 9 is a top plan view of FIG 7;

The broken line showing of a fragmentary portion of a truck cab is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for an exterior shell of a truck cab step unit, as shown and described. 